What Is a Gram Stain?

A gram stain
is a type of microbiology or laboratory test that determines whether bacteria are
present. It also determines whether bacteria are gram negative or gram
positive. The difference between gram negative and gram positive bacteria can
be important when determining appropriate treatment for an infection. Gram
stains are performed on various types of specimens including blood, tissue,
stool, and sputum.

What Does a Gram Stain Do?

In some
instances, it isn’t clear whether an infection is bacterial, fungal, or viral. And
these types of infections may be treated very differently. In addition,
different types of bacteria may require different treatments. A gram stain lets
physicians determine whether bacteria are causing an infection and what type of
bacteria is present.

Who Benefits from a Gram Stain?

Anyone
who has a bacterial infection or a suspected bacterial infection is a candidate
for a gram stain test. A doctor frequently orders it along with a culture if
someone has symptoms of an infection.

What Are the Side Effects of a Gram Stain?

A gram
stain has very few side effects. The types of side effects that can occur depend
on the type of sample and method used for obtaining the sample. Collecting some
types of samples, such as a stool sample, has no side effects. Gram stains that
use a blood sample, meanwhile, can sometimes cause side effects due to the
blood draw, such as bruising.

How Is a Gram Stain Administered?

In order
to perform a gram stain test, a sample of body fluid or tissue is needed. Collection
methods vary depending on the type of sample. For sputum or mucus, a patient
can cough up a sample into a specimen container. In other instances, a blood
sample can be collected with a blood draw.

What Are the Benefits of a Gram Stain?

The main
benefit of a gram stain is that it allows the doctor to determine the best type
of treatment for an infection.

What Are the Risks of a Gram Stain?

There are
no known risks of performing a gram stain with a sample of urine, stool, or
mucus. If a gram stain uses a blood or tissue sample, there are a few risks
related to the blood draw or removal of the tissue, such as excess bleeding or
infection (University of
Rochester Medical Center).

How Should You Prepare for a Gram Stain

There is
often no special preparation needed to give a sample for a gram stain.

What Is the Outlook After a Gram Stain?

The
prognosis for people who have a bacterial infection identified through a gram
stain varies greatly. Gram stains that are performed early can help improve the
ultimate outcome.

What Are the Results of a Gram Stain?

A negative
gram stain test means that there are no bacteria present. A positive gram stain
indicates the presence of bacteria.

Because
of the staining technique, gram positive bacteria will be seen under the
microscope as purple and gram negative bacteria will be viewed as pink. The
shape, size, and quantity of bacteria present will also be evaluated.

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